1) Field of the Invention
This invention relates to a thin film magnetic head, a magnetic head device and a magnetic disk driving device.
Related Art Statement
A floating type thin film magnetic head has usually an inductive type electromagnetic conversion element as a writing element and a magnetoresistive effective element as a reading element in an air outflow side of its slider. The inductive type electromagnetic conversion element is covered with a protection film which is made of an inorganic insulating material such as alumina and constitutes an outermost surface layer of the magnetic head in the air outflow side.
The inductive type electromagnetic conversion element includes a first and a second magnetic films, a gap film, a coil film and an insulating film, etc. The edge portions of the first and second magnetic films, which are opposed each other via the gap film in the air bearing side (hereinafter, called as xe2x80x9cABSxe2x80x9d) of the slider, constitutes a pole portion for writing.
Moreover, the second magnetic film rises up with inclination of a given angle on the gap film, extending backward from the ABS with maintaining a minute space for the first magnetic film, and is joined with the first magnetic film.
The coil film passes through the space (inner gap) in between the first and the second magnetic films and winds spirally around a backward joined portion between the first and the second magnetic films. Both ends of the coil film are drawn out to the outside via a terminal conductor(bump). The inner gap in between the first and the second magnetic films is embedded by the insulating film. The coil film is embedded in the insulating film. The second magnetic film is formed on the insulating film.
In writing for a magnetic disk by the above thin film magnetic head, a current for writing is supplied to the coil film of the inductive type electromagnetic conversion element.
In this case, however, the coil film develop a heat. As mentioned above, since the coil film is embedded in the insulating film made of an organic insulating material, and the insulating film is covered with the protection film made of alumina, etc., the coil film can not discharge the heat effectively. Therefore, the developed heat is charged in the thin film magnetic head, and thus, expands the insulating film thermally.
The thermally expanded insulating film presses and expands the protection film to the outside. The expansion of the protection film influences the ABS, resulting in the expansion of the part of the ABS corresponding to the inductive type electromagnetic conversion element. Moreover, the developed heat in the coil film expands the first and the second magnetic films adjacent to the insulating film thermally. As a result, the edge of the pole portion, not much strongly fixed, composed of the first and the second magnetic films is expanded in the ABS side. The expansion degree often reaches 10 nm.
In a magnetic disk driving device having such a thin film magnetic head, for high recording density, the floating space between the ABS of the thin film magnetic head and a magnetic disk is narrowed gradually to 40 nm, 30 nm, 20 nm or 10 nm. Therefore, the above expansion in the ABS can easily crash the thin film magnetic head itself and the magnetic disk or damage the magnetic recorded data, resulting in the deterioration of the reliability of the magnetic disk driving device.
For solving the problem, Kokai Publication Kokai Hei 4-366408 (JP A 4-366408) discloses that a recessed portion is formed on the surface of a protection film in a medium opposing surface. The recessed portion is so formed that the surface of the protection film is polished flat with heating the thin film magnetic head element and thereby, expanding the protection film.
However, the disclosed technique dose not repress the thermal expansion of the protection film, but allows the thermal expansion as far as the protection film does not expands beyond the flat ABS by retreating the protection film from the ABS in advance. Therefore, the disclosed technique can not solve the above problem.
Moreover, in the above technique, the complicate process is required that the protection film is flattened on the basis of the assumed expansion degree due to the developed heat at a recording operation. In addition, the configuration of the slider, particularly the geometrical shape of the ABS is specified to a give shape, and thus, the ABS can not have another geometrical shape for improving the floating performance. Then, in the above technique, a means to repress the thermal expansion of the edge of the pole portion is not disclosed.
It is an object of the present invention to provide a thin film magnetic head in which the thermal expansion in the ABS due to the developed heat at a recording operation can be repressed.
It is another object of the present invention to provide a thin film magnetic head in which the thermal expansion in the ABS due to the developed heat at a recording operation can be repressed absolutely without a special manufacturing step.
It is further object of the present invention to provide a thin film magnetic head in which the thermal expansion of the edge of the pole portion as well as the protection film can be repressed absolutely.
For achieving the above objects, a thin film magnetic head of the present invention includes a slider, at least one inductive type electromagnetic conversion element and a protection film.
The inductive type electromagnetic conversion element includes a first magnetic film, a second magnetic film, a gap film, a coil film and an insulating film which are supported by the slider. The forefronts of the first and the second magnetic films in the ABS of the slider are opposed each other via the gap film, and thereby, constitutes the pole portion of the thin film magnetic head.
The first magnetic film is extended backward from the pole portion on the basis of the ABS. The second magnetic film is extended backward from the pole portion on the basis of the ABS with maintaining a minute space for the first magnetic film, and is joined with the first magnetic film.
The space (inner gap) in between the first and the second magnetic films is embedded by the insulating film, on which the second magnetic film is formed. The coil film is embedded in the insulating film, and wound spirally around the backward joined portion between the first and the second magnetic films. The inductive type electromagnetic conversion element is covered with the protection film entirely.
Herein, provided that the minimum thickness on the second magnetic film of the protection film is xe2x80x9cAxe2x80x9d and the maximum thickness between the inner space of the insulating film is xe2x80x9cBxe2x80x9d, the relation of xe2x80x9c1xe2x89xa6(A/B)xe2x89xa62.5xe2x80x9d is satisfied.
As mentioned above, in the thin film magnetic head of the present invention, the forefronts of the first and the second magnetic films in the ABS of the slider are opposed each other via the gap film, and thereby, constitutes the pole portion of the thin film magnetic head. Moreover, the second magnetic film is extended backward from the pole portion on the basis of the ABS with maintaining a minute space for the first magnetic film, and is joined with the first magnetic film. Therefore, a thin film magnetic circuit with the pole portion for writing in the ABS side is composed of the first and the second magnetic films and the gap film.
Moreover, the coil film passes through the space (inner gap) in between the first and the second magnetic films and winds around the backward joined portion between the first and the second magnetic films. Therefore, when a current for writing is flown in the coil film, a magnetic flux for writing is generated in the thin film magnetic circuit composed of the first and the second magnetic films and the gap film, thereby, a magnetic field for writing is generated at the edge of the pole portion. A magnetic disk can be magnetically recorded by the magnetic field.
Since the coil film is embedded in the insulating film and the second magnetic film is provided on the insulating film, it is electrically insulated from the first and the second magnetic films. Moreover, the whole inductive type electromagnetic conversion element is covered with the protection film.
Moreover, in this invention, the minimum thickness A on the second magnetic film of the protection film and the maximum thickness B between the inner gap of the insulating film satisfy the relation of 1xe2x89xa6(A/B)xe2x89xa62.5. Therefore, the expansion degree of the protection film can be repressed to 3 nm or below. As a result, even though the floating space between the thin film magnetic head and the magnetic disk is narrowed to 40 nm, 30 nm, 20 nm or the like, the magnetic head and the magnetic disk are not crashed and the magnetically recorded data are not damaged, so that the reliability of the thin film magnetic head can be developed.
According to the present invention, the thermal expansion of the protection film due to the developed heat at a recording operation can be repressed by selecting the minimum thickness A on the second magnetic film of the protection film and the maximum thickness B between the inner gap of the insulating film without a special manufacturing step. As a result, the thermal expansion of the edge of the pole portion as well as the protection film can be repressed.
This invention relates to a magnetic head device and a magnetic disk driving device which have the above thin film magnetic head.
The other objects, configurations and advantages will be explained in detail, with reference to the attaching drawings in embodiments.